We have assessed the rosette technique as a method for studying the kinetics of the anti-vibrio and anti-toxin immune responses in experimental cholera in the chinchilla. The technique was found to be very sensitive (at least a five-fold increase in rosette forming cells has been demonstrated in spleens of immunized chinchillas above the levels in non-immunized chinchillas), and the technique has been adopted as a standard procedure. Kinetic studies on anti-vibrio response in chinchillas are in progress. We have observed about a three-fold increase in RFC in Peyer's patches at the peak of the response (day five) without concomitant increase in spleen and mesenteric lymph nodes. The development of a lytic assay to complement the rosette assay is in progress. Fractionation of chinchilla immunoglobulins has been achieved; these fractions will be used to raise anti-immunoglobulin sera as soon as characterization of each fraction is complete. The anti-immunoglobulins will be used to develop lysis by those immunoglobulins (IgG and IgA) which are inefficient or incapable of lysis of target cells unless complexed with another anti-globulin. These anti-immunoglobulins will also be used to quantitate anti-vibrio and antitoxin antibodies in serum and intestinal fluid of experimental animals. BIBLIOGRAPHIC REFERENCES: Blachman, U., Goss, S.J., and M.J. Pickett. Experimental cholera in chinchilla, J. Infect. Dis. 129: 376-384, 1974. Davidson, C.F., and C.R. Parish. A procedure for removing red cells and dead cells from lymphoid cell suspensions. J. of Immunol. Methods 7: 291-300, 1975.